Bob,
I'm having my head shaved on my '74 TR6 to 3.416 inches to give me around a
9.5:1 compression. Is it safe to assume that my stock pushrods will no
longer work?
Thanks in advance.
Mark Bullard
Kailua, HI
>On Tue, 22 Apr 2003 13:12:04 -0400 (EDT) "Robert M. Lang"
<lang@isis.mit.edu> wrote.
>On Tue, 22 Apr 2003, Alan & Debbie Lindner wrote:
>
>> I believe my head was milled. Does anyone have a measurement
>> of the the adjustment threads length with a narrow nut on for a
>> standard or milled head.
>
>Ummm... this is one reason that you need to shorten your pushrods if the
>head is milled. What happens is that you arrive at the proper valve lash
>by backing the adjusting screw nearly all the way out...
>
>The Competition Prep Manual shows how to make a dummy pushrod to get the
>proper pushrod length, and you then need to obtain a tubular pushrod set
>to shorten (or you can buy them already shortened).
>
>Note: the Euro Spec motors ran higher compression heads from the factory.
>so there's a euro spec stock pushrod that some folks sell (I recall BPNW
>having them sometime in the past). The stock pushrods are not tubular
>type.
>
>> Also, can I just measure the height of the head to get an idea of
>> how much has been milled?
>
>Well, you might be able to, but you have to know what you started with.
>
>For example, I had over .110 milled of my stock 74 TR6 head and it got me
>to about 9:1... all the late heads are 'real thick" whereas the '72 head
>would only need less than .050 milled off to get over 9:1 (seeing that it
>starts life as more than 8:1 and the '74 is a 7.75:1 stock compression
>ratio.
>
>As a generaly rule, if you measure from the deck to the surface that the
>valve cover seal to, you come up with a "thickness", and you can
>approximate the compression ratio. But the only true way to measure is to
>get a burrette and pull the head and measure the volume of the combustion
>chamber (and don't forget that that head gasket needs to be included in
>your computations.
>
>> Alan
>
>regards,
>rml
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